10. f1b5 It's difficult to say which is the best square for the bishop. It's also not clear what White is going to do after …a7-a6, whether he takes on c6 or comes back. 10... a8c8  11. e1g1  11... a7a6  12. b5e2 Nakamura decides to retreat with the bishop. The other plan is to capture on c6 and play with a quick d2-d4.